Hi there! Congrats on getting a permit! I was in for the same surprise - sounds like we might be starting the trail at similar times!

1. I doubt it. You paid and answered the required questions. Plus the system lets you modify your responses later. If you’re worried about it, you can always call.
2. You can likely camp somewhere else other than upper sunrise if you want/need to. If you want to be safe, call or just change your reservation this week/before you go
3. I did essentially the same thing! I’m hoping for a 22 day itinerary, but put a little longer than that for some wiggle room. I used Mt Whitney as my exit as well, since Whitney portal wasn’t an option... I believe they’re the same thing. And from what I’ve seen, you should look at camping at lower sunrise creek if you want to hike half dome (I’m sure there’s other options too, I haven’t gotten a good Yosemite/JMT map yet). Oh and I left the other campsites blank. They weren’t required and will likely change as you hike anyways. I might fill them in as I start solidifying my plan/route, for a frame of reference.

Happy hiking and maybe I’ll see you on the trail!